Have an addition that needs heating, it is far away from the furnace, the basement of existing is finished and the existing furnace could not handle the load.
His suggested solution is to pipe(3/4″) hot water from the water heater to an Air Handler in a closet within the addition with ducting thru the attic to the different rooms. This would give the addition its own zone and is supposedly extremly efficient.
Plus the homeowner can add a 1.5 tonne roof-top A/C unit for 800$ piped to the air handler. Only draw back is that the hotwater tank would have to be upgraded to a fast recovery one. (Homeowner rents from local util, so even thats not a big issue). There will be hotwater needed for a bathroom in the addition anyways.
Sounds to Good to be true, is it? I’ve never used this system, can anyone shed some light on it for me?
Thanks in advance.
J.
Replies
For that small a space, a utility close might work better. Get a "stand-up" (vertical) apartment unit with heat. For the 8K c.f., the unit would almost be short enough to 'sneak' a 20 water heater under it. You could then get all of the utilities for the addition into 33" x 30" with a louvered 2-0 door to finish. Downside is that the units can be noisy.
The drawback to using a water heater for heat is that it will have to be set closer to 180° to supply hot enough water. This is significantly hotter than is recommended (or preferred) for domestic use. (Also, a code violation in some jurisdictions.)
I'd recommend just adding heat to the attic airhandler, and using either a 20 gallon or a demand heater for the hot water.
I agree w/ Capn Mac, if you use the water heater for space heating, you will need to set the temp too high for domestic use, so you'd need a thermostatic mixing valve, like leonard, or lawler, to set the right temp going to the DHW fixtures.
Using a hot water heater to provide heat is not recommended. It is the poor mans way of doing it. I would never recommend doing it that way and if a customer requested it, I would not do the job. Do it right and add another zone from the heating system. If the present system is not able to handle the extra space then replace the system with one that will.
I appreciate all the feedback from everyone.
Poor mans way of doing it eh? well these people arn't extremely well off and i just cant see ripping up their finished basement and replacing their furance to do it the "right way". I'm still leaning towards the hotwater heater way, there are several developments around here that use it and from whjat I hear no negative results.
Increasing the water temp is a suprise to me thou, they have 3 toddlers and i'm wary of doing that?
Any other responses or considerations? Any other pitfalls of using this system? I've tried to do some preliminary internet research but am coming up short, any suggested sites?
Thanks again,
J.
Who is the architect that designed this addition? Did he even consider how the new space was going to be heated? "One measurement is worth a thousand expert opinions"
I wish, all homeowner....
Nothing wrong with the concept in general.
Here's the BIG question. Do you want to assume the liability that this system might KILL the clients????
Yes, you read that right. If installed the way MANY slobs advocate installing it YOU assume a LOT of liability. Liability that your insurance WILL NOT COVER!
And it has happened. And it will happen a lot more.
I hope I got your attention. Because this is a serious issue. (I fully expect some geek to come here and argue with me... That's OK. I am standing on solid research and proven facts. They are going on what a cheap-a$$ idiot told them would work)
Here is the #1 issue. The heating loop must be a closed loop and completely isolated from the domestic water via a heat exchanger. The loop between the heat exchanger and the water heater MUST also be circulated with a timed circulator of be close coupled so that a tiny bit of thermal flow always happens. The last way is easier, cheaper, and more reliable than the timer method.
Do it right or assume all the RISKS!
I may be wrong on your insurance covering it. Just find out if they will cover death caused by your negligence to install this system in a manner proven to have killed people and which is contrary to established standards?
I am not trying to be a jerk. This is improtant and I want to convey that in as strong a manner as possible.
Think i will advocate a closed system with a 20-23gallon tank running at a 180 degrees anyways. I will dbl check on the pump but i think that my heating guy already included it in design but will dbl check.
Thanks.
Know of any good online resources for this.....?
"I fully expect some geek to argue with me...The heating loop must be a closed loop and completely isolated from the domestic water via a heat exchanger."
Wet: Some geek here. Hi.
I agree that many code authorities would require a heat exchanger between a HWH and the heating system. But some people are not within a jurisdiction that requires inspections. So I would have said "may have to" rather than "must".
I am aware of the hazard of adding chemicals to a heating system and of those chemicals (like gycol) getting into the potable piping through a defect in a single wall heat exchanger. Or, of course, if one were stupid enough to add chemicals to an open system. But, heck, one could pour something nasty into a potable-only piping system so maybe codes don't save us from everything.
Yet some manufacturers give schematics for HWHs used for space heating only and for both space and potable water heating - with and without heat exchangers (with caveats about local codes).
What other (than the addition of chemicals) hazards are there of an open system? I really don't see hazards that don't exist in other heating systems. Thanks.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
Leggionaires (sp?) has resulted from such systems and has caused deaths. Thus the MUST in my response. Hey... I am coming your way this summer for 3 weeks. Am doing a job in Wasilla.
how would this introduce legionaires disease, i think i may be talking about a different system, ther is no standing water
Why is there no standing water? Are you draining it during the summer months? I must be missing something here.
There have been some problems with this system when water is allowed to stand in the heating loop over the summer. Conditions within the loop with normal hot water temperatures (120-140 F) can be almost ideal for legionella and legionella is present in almost all water. That said the system can be very cost effective and safe, several hundred were retrofitted at the AF Academy in the 80's. Key to a safe system is to periodically circulate the loop. Daily is adequate. You can circulate the loop when the fan is off for perhaps 5 minutes.
There were a number of Legionella cases in hospitals, including St. Anthonuy's here in Denver, due to low temperature stagnant water storage tanks. For that reason hospitals are now required to use 180 F storage tanks and tempering valves. I am not aware of any documented residential cases. In the hospital cases I am aware of all were from taking showers with the polluted water. A leak in a hot water coil within the air stream could introduce the same sort of conditions. In my opinion a contributing factor was the disconnection of circulation pumps as an energy conservation measure.
It would be good practice to bump your hot water temperature to 160 F(usually the practical max on residential heaters) or higher when returning from a vacation and then run a full tank of water thru all of the system before using any particularly for showers.
One practice that concerns me somewhat is the use of DHW in radiant floor loops. It is not practical to flush some of these loops with higher temperature water for fear of cracking the floor.
As to the requirement for increasing the water temperature this is not required nor is it practical with residential tanks. The hot water heating coil in the air handler must be sized for use of 120-130F water.
Sorry for the lecture.
Edited 5/2/2003 10:39:43 PM ET by JANATION
Edited 5/2/2003 10:42:10 PM ET by JANATION
My friend Dave Yates has documentation of this happening in residential conditions. I'll contact him and ask for details.
I agree that circulating the water would resolve the issue. But do you really want to risk your health on a circulator that is failure prone or that someone decided to disconnect to save electricity. The types that put in open loop systems will most likely install CI circs instead of bronze and that would guarantee failure.
For the record, I am all for heating with WHs. But I will fight against open loop systems as long as I live unless concrete evidence proves me wrong. At this point ALL evidence backs me up.
If its a closed system it will definately have to be drained for the summer, hmmm quite the expectation of the homeowner and any future buyers.
why so?
Code in Canada does not allow the use of water heaters as a stand-alone heating source.The efficiency of water heaters vs. boilers is another consideration.
Where in Canada does code not allow that? It's allowed in my area (Ontario). Or... Which code is it that disallows that?
Just curious - Brian.
CSA B214 Installation Code for Hydronic Heating Systems. Water heaters certified for use in combination systems shall be used for potable water or potable water and space heating application only. Apparently, the logic is that they are not certified for use as a space heating appliance. Enforcement is another issue. Saskatchewan just came out with amendments to the gas code to allow the gas inspectors jurisdiction over boilers under 400,000 btu and/or installations where boiler inspectors may not be required to inspect.Up to now,water heaters as a source of heat were ok. Not any more here.Going to be a lot of ticked off customers.The issue of insurance and liability also needs to be considered.
very interesting information guys thank you all. i have never done a radiant heating system and have been meaning to learn more about it and this is a start. i was totaly unaware that you cannot use a water heater for the heat without a closed loop and a heat exchanger. i recently installed an 80,000 btu forced air furnace in my last project, it was less then $600 dollars at local plumbing supply. ordered plenums from local sheet metal shop, $110 dollars plus cost of flexible and rigid duct material, i forget but not that much it occurs to me you could upgrade existing system relatively cheap and it is simple, check for gas leaks, plug in through gfci and you are code compliant
From what i understand cpl of new townhome developments in my area are using them as well. (Hamilton)
Rich1 - Just so I'm clear about this - Does that mean that you can use IFR heat with a HWH only if you also use the HWH to supply the domestic water as well? Is that how the code reads? Interesting. What would you suggest the reasoning behind this is?
Wet Head Warrior - an open system doesn't rely on any pumps at all in the summer to continuously refresh the water if it is set up so that the city water comes into the HWH after it goes through the floor first. Water pressure provides the drive. I'm sure that an air handler could be configured in the same way. I was also under the impression that stainless steel pumps were the way to go in open systems. It's standard equipment with Radiantec, a system which has previously been flippantly poo-pooed in this forum.
Another variable in the opposition of open systems is the initial quality of water that enters the system. Microbial activity can only occur in areas where microbes are already present. So if the source of water is, say, a well which has marginal water quality, I would be more concerned about contamination.
Like you, I as well would also like to see some "good science" applied to the question of stagnation. In a city water situation biological reproduction is impeded by dissolved chlorine gas which is present as long as water pressure is maintained in the pipes or until it is used up by its biocidal action. (Chlorine doesn't kill EVERYTHING though.) Normally there is a chlorine residual left over in water which takes care of any contaminants which may have survived the initial dose (or which have been introduced somewhere along the pipe after it.)
Stagnation is a fairly common occurrence, such as in houses where a bathroom in a rarely-used guest bathroom has fixtures which may not be used for months, or, as Janation points out after an extended vacation, I think that were a problem to occur that the real culprit would be poor initial water quality.
Since you are a professional in the business and the jury is still out on this issue I think that you are wise to reduce your exposure to liability in a litigious environment by erring on the safe side, though. The status quo is always the safe way to go.
Regards - Brian.
Brian, I have no idea what the ultimate reasoning is against stand alone use other than they have not been tested and certified as a heating appliance.If they have a set of taps hooked up, you are good to go. Personally and professionaly, I would not use it that way unless there is a heat exchange used.
Edited 5/19/2003 2:08:28 AM ET by rich1
There are some issues about mixing potable water with a heating loop but codes allow it in most states. However, if I was doing it, I would spend the extra $200 and buy a water heater dedicated to heating the room and then I would not have to address those issues.
2nd heater and closed loop might be a really good idea the we can crank the heat without worry as well.
JLC has had an article on this and a couple of Q&A's. But I think that all of them have been for radiant heat where the water temp is lower.
jlconline.com and then Research to find the articles.
Thanks, i will check it out.